Drying and gas or vapor contact with solids – Apparatus – Rotary drums or receptacles
Patent
1988-03-31
1989-06-13
Bennet, Henry A.
Drying and gas or vapor contact with solids
Apparatus
Rotary drums or receptacles
34 10, 226 97, F26B 1300
Patent
active
048379476
DESCRIPTION:
BRIEF SUMMARY
CROSS REFERENCE TO RELATED APPLICATION(S)
This U.S. application stems from PCT International Application No. PCT/DE87/00336, filed July 30, 1987.
TECHNICAL FIELD
The invention relates to a device for acting upon and guiding in hovering manner webs of material, in particular webs of paper, with air or another flowing medium, mainly for drying the web. An air duct or the like is provided which comprises at least one nozzle region, extending over the width of the web, with a curved wall surface formed by a boundary of the air duct and a flat wall surface which is adjacent thereto and runs substantially parallel to the plane of movement of the web.
STATE OF THE ART
In the known devices, in which air is blown against a moving web in order to dry the web, the respective air outlet opening is constructed as a nozzle slit extending over the width of the web (DE-C2 28 36 103). Such slits pass from so-called nozzle tanks and are limited on one side by a substantially flat wall and on the other side by a wall having a curved portion and an adjacent straight portion running parallel to the plane of the web.
Known nozzle tanks with nozzle slits are normally produced from sheet metal. Owing to the relatively small wall thickness, the metal sheets tend to warp and to become distorted under the various operating conditions, in particular under changing temperatures and pressure conditions. This also leads to undesirable changes in the region of the nozzle slit so that the quantity of air and possibly the flow parameters also vary and this can be very disadvantageous, depending on the extent of such influences.
STATEMENT OF THE INVENTION
An object of the invention is to take account of existing problems and shortcomings and to provide a device of the type mentioned at the outset which, with a simple design, affords operating conditions which are as stable as possible even under varying temperature influences. In particular, the device should also be very convenient to produce. Furthermore, the invention aims to provide an advantageous configuration of the device in detail. Further associated problems with which the invention deals follow from the respective description of the solution set out.
In a typical device, the invention proposes that individual outlets for air be provided in wall sections which define the air duct opposite respective guide surfaces for the air flow in the nozzle region on either side of a transverse plane running in the longitudinal direction of the air duct and perpendicularly to the plane of movement of the web.
The outlets can be designed as mouth pieces, individual nozzles or the like. In a very advantageous design, holes in the wall sections of the air duct are provided as outlets for the air.
The device according to the invention can be produced very simply and allows perfect operation even under varying operating conditions. Even if wall sections are displaced slightly under undesirable conditions, the quantity of air still remains constant. The flow conditions remain in the manner desired at any given time. Nevertheless, the device can easily be adapted to different requirements. Depending on the circumstances and requirements of the respective application, a nozzle region of the above-mentioned design can be provided at one or more points of one and the same air duct, as viewed in the longitudinal direction of the web.
A desirable design is characterised in that wall sections provided with two outlets are arranged immediately opposite one another and each of these wall sections forms, at least in part, a guide surface for air flows issuing from the outlets of the other wall section. Particularly desirable conditions for numerous cases can be achieved with such a design. It serves, in particular, to produce air flows according to the so-called Coanda effect.
It may be advantageous, in principle, to offset the outlets in one wall element relative to the outlets in the other wall element, in particular in the lateral direction and/or in the height direction.
Air outlets can be provi
REFERENCES:
patent: 4472888 (1984-09-01), Spiller
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